Many electronics systems employ self-test diagnostics (i.e., tests that check the correct operation of hardware or software). An important aspect of such testing is to alert a technician upon detection of a fault. Industry-accepted mechanisms for providing instantaneous visibility of a fault include light-emitting devices or diodes (LEDs) and panel displays. Commonly, an LED is placed near a particular module or component within an electronics system to produce an intuitive association between the two. Illuminating the LED thus operates to point directly to the actual faulting component.
Often, a faulting component is part of a sub-assembly housed within a larger electronics assembly. As a result, the illuminated LED is often hidden from view of the technician. Thus, to alert the technician of the faulting component within the sub-assembly, an exposed panel or bulkhead of the electronics assembly has an exposed visible indicator to notify the technician. Although this exposed indicator can direct the technician to the sub-assembly that is experiencing a fault, the technician cannot determine which particular component within the sub-assembly is at fault without uninstalling the sub-assembly from the larger electronics assembly.
Uninstalling the sub-assembly, however, often electrically disconnects the sub-assembly from the larger electronics assembly and, thus, from its source of power. Consequently, any LEDs within the sub-assembly that were lit while the sub-assembly was installed are no longer lit after the sub-assembly is removed. Without electrical power, the LEDs are unable to serve their purpose identifying faulting components.